add a bit about hotplugging

svn path=/nixu/trunk/; revision=4515

howto

@@ -79,3 +79,22 @@ NixOS machine (needed for mingetty). Alternatively, do:
 # touch /etc/login.defs
 
 - relaunch init
+
+
+  Making hotplugging work
+
+Many devices are controlled by so called "hot plugging". The kernel executes
+a program -- usually /sbin/hotplug, but this is configurable at boottime by
+setting the right path in /proc/sys/kernel/hotplug -- when a new device is
+added to the machine. This program makes sure the right kernel modules are
+loaded and optionally, if enabled, sends a message to udev to create the right
+device node in /dev (NOTE: this is not enabled in NixOS right now).
+
+- install hotplug package
+  - make symlinks /etc/hotplug, /etc/hotplug.d, /sbin/hotplug (TODO: make
+    this pure)
+  - make sure the kernel and additional modules are prepared well (currently
+    this is hackish, but workable: see kernelscripts/make-kernel.sh for an
+    example)
+  - (optionally:) launch udev
+  - plug in a device